For a great many years, it has been the conventional practice to shear sheep with power operated handpieces which comprise a body fitted with a comb and with a pivoted member, termed a fork, by which a cutter is oscillated across the comb face to sever the wool. The fork is actuated by an overhead driving mechanism from which rotary motion is transmitted by a rotary shaft comprising successive sections connected by universal joints or the like.
The conventional handpiece is relatively large and heavy and its aforesaid jointed driving shaft limits its maneuverability and so restricts the positions in which the animals may be arranged during the shearing operation.
Although, notwithstanding these limitations, the conventional mechanically driven handpiece has been successfully used for many years to shear sheep in the conventional manner, it does not permit of the degree of maneuverability which is desirable in all circumstances, but which is more important, if not necessary, when for example, it is desired to shear sheep which are inverted and suspended by their four legs from a conveyor as disclosed for example in the specifications of my prior Australian Pats. Nos. 252521 and 410488. Such conveyor shearing procedures are now sometimes compendiously designated "chain shearing".
During recent years there have been various proposals for incorporating an electric, air driven or hydraulic motor in each handpiece but in general, such motor driven handpieces are relatively bulky and expensive and in most cases are also subject to other disadvantages of one kind or another. In all such proposals known to me the motor has a rotary output shaft for a crank or other actuating device for the, pivoted fork.